Reaction #68721

Reaction equation

4-Bromo-2-methylphenol

4,4′-(bicyclo[2.2.1]hept-5-en-2-ylmethylene)bis(2-methylphenol)

Triethylamine

formic acid

→

4,4′-((5-(4-hydroxy-3-methylphenyl)bicyclo[2.2.1]heptan-2-yl)methylene)-bis(2-methylphenol)

Yield 54.0%

Solvents

ethyl acetate

DMF

Conditions

Workup

1. 1
   Otherequipped
2. 2
   Otherreaction vessel
3. 3
   Otherto give a suspension
4. 4
   OtherDuring, the course of the reaction
5. 5
   Otherrose to 82° C.
6. 6
   OtherAfter the initial exothermic reaction
7. 7
   OtherThe cooled reaction mixture
8. 8
   Washwashed with water (160 mL)
9. 9
   Otherto remove DMF
10. 10
    DryingThe organic layer was dried over anhydrous MgSO4
11. 11
    OtherThe crude mixture was purified by preparative TLC

Procedure

Under a nitrogen atmosphere, 4-Bromo-2-methylphenol (4.69 g, 25.1 mmol), (tris-o-tolylphosphine)2PdCl2 (0.377 g; 0.480 mmol), and 4,4′-(bicyclo[2.2.1]hept-5-en-2-ylmethylene)bis(2-methylphenol) (5.14 g; 16.0 mmol) were charged to an appropriately sized and equipped reaction vessel. DMF (80 mL) was added to this reactant mixture to give a suspension. Triethylamine (11.0 mL, 78.9 mmol) and formic acid (2.30 mL, 60.9 mmol) were added to this suspension and then heated to 75° C. in an oil bath. The reaction mixture turned from its original orange suspension to pale yellow and became clear. During, the course of the reaction, the temperature of the reaction mixture rose to 82° C. and turned darker, and a gas evolved very slowly. After the initial exothermic reaction ceased, the reaction mixture was stirred overnight at 75° C. After this time, the reaction mixture was a clear, pale yellow solution with black particles. The cooled reaction mixture was diluted with ethyl acetate (80 mL) and washed with water (160 mL) to remove DMF. The organic layer was dried over anhydrous MgSO4. The crude mixture was purified by preparative TLC using a hexanes/ethyl acetate mixture (50:50) as developer to afford 3.7 g of 4,4′-((5-(4-hydroxy-3-methylphenyl)bicyclo[2.2.1]heptan-2-yl)methylene)-bis(2-methylphenol) (54% yield). The identity of the product as PP429 was confirmed by LC-MS (ESI) and proton NMR.

Source